The GPS (Global Positioning System) is a global navigation satellite system for determining position. It has been developed by the US Department of Defense in the 1970s. GPS has been fully functional since the mid-1990s and, since artificial signal degradation was switched off in 2000, it has also enabled civil users to achieve an accuracy of often better than 10 meters. The accuracy can be increased to values in the centimeter range or better using differential methods (differential GPS / DGPS) in the vicinity of a reference receiver. With the satellite-based augmentation system (SBAS), which distributes correction data via geostationary satellites that cannot be received in the polar regions, accuracies of one meter are achieved across the continent. GPS has established itself as the world's most important positioning method and is widely used in navigation systems.